This invention relates to a film cartridge.
Cameras which use a pop-in cartridge which encloses the film have been known for many years, for example as manufactured by Kodak under their trade mark "INSTAMATIC". Such cameras are extremely easy to operate, generally requiring the user only to insert the film cartridge into the camera, close the back, wind the film on and then take a photograph.
The cartridge comprises a casing, with the unexposed film stored in a film supply chamber of the casing in a roll and connected to a spindle in a take-up chamber of the casing via a film transport path in which a film exposure window is disposed. The film includes a backing sheet indicating the picture frame number which is visible through an opening in the casing, thus obviating the need for any external mechanism in the camera for performing this function.
A winder on the camera engages the spindle to advance the film between frames and the film is provided, at frame intervals, with an opening on one longitudinal side which is engaged by a spigot of the camera. As the spigot engages a side of the opening, the spigot is pulled to an upright locked position which holds the film at the correct position to take a further photograph. The action of movement of this spigot also cocks the shutter allowing a picture to be taken. When the shutter release is pressed, this automatically releases the locked spigot thus allowing the film to be advanced again.
Although the film cartridge is of somewhat more complex construction than ordinary roll film, this does allow the camera to be of very simple construction, thus leading to reduce manufacturing cost and providing an inexpensive, simple to operate camera suitable particularly for children.
The film format used in such cameras is what is termed "126" format film which produces a 28 mm square frame negative. While capable of producing acceptable results in good light, 126 square frame film does not produce such an aesthetically pleasing picture format as, for example, standard 135 or 35 mm film which uses a negative of 24 mm width and 36 mm length, i.e. in a rectangular format.
Proposals have been made to provide the advantages of a rectangular format with 126 format film by restricting the exposure area to province a negative with a length of 28 mm but with a reduced width to produce a negative of the same side to edge ratio as 135 format film but of a reduced size. It is a disadvantage of such a proposal, however, that if the negative is enlarged by conventional processing equipment, reduced size prints are obtained and it is necessary to provide special equipment to make the additional enlargement necessary to provide a "full size" prints from the reduced size negative.